The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work described herein, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art.
Traffic signal recognition refers to the process of identifying and marking areas of an image frame that include a traffic signal, for example, a traffic light. A camera obtains the image frames, which are processed individually. Traffic light candidates and areas in the immediate vicinity are determined based on matching an actual traffic template with a template from a template library. The accuracy of traffic signal recognition may be increased by using adaptive templates. Adaptive templates are adjusted according to an expected size of the traffic light candidate and/or the actual traffic light template, which is based on a distance of a vehicle from the traffic light candidate. A best matched template is validated based on a number of possible templates that are matched in size to the actual image frame area corresponding to the traffic light candidate. For example, one of the possible templates may be used when a green circle in the traffic light candidate is illuminated and another of the possible templates may be used when a red circle in the traffic light candidate is illuminated. This is because the red and green circles are at different locations within the traffic light housing.